Since a high-voltage battery is mounted on a vehicle such as an electric automobile or a hybrid automobile, there is a need to provide a ground fault detector in order to ensure the safety of a passenger.
As an example of the ground fault detector, for example, PTL 1 discloses a vehicle ground fault detecting apparatus which highly precisely detects a ground fault of a DC power supply (battery). The vehicle ground fault detecting apparatus applies a rectangular wave pulse signal to one end (a measurement point A) of a coupling capacitor, obtains a measurement voltage when the rectangular wave pulse signal is an H level and a measurement voltage when the rectangular wave pulse signal is an L level, and detects an occurrence of a ground fault based on a difference between the measurement voltages.